Section-switch.



H, w. DAVIS.

SECTION SWITCH.

APPLICATION FILED APR. 2?. 191's.

Patented Sept. 11, L917.

BY w Lmmw" ATTORNEY xxx I WITNESSES: & M v

NTED @TAE@ ATENT HARRY W. DAVIS, 01? SWTSSVALE, PENNSYLVANIA, ASSIGNOROF ONE-HALF TO WILLIAM G. FROST, 01? EAST PITTSBURGH, PENNSYLVANIA.

SECTION-SWITCH.

Specification of Letters Patent.

Patented Sept. 11, 1%1'7.

Application filed April 27, 1915. Serial No. 24,234..

To all whom it may concern:

Be it known that I, HARRY W. DAVIS, a citizen of the United States, anda resident of Swissvale, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Section-Switches, of which the following is a specification.

My invention relates to section switches for electric trolley systems,and it has special reference to section switches for use in mine trolleylines, where the trolley condoctor is located near the roof of the mineand where it is customary to insert a sectionalizing switch in each ofthe branch conductors thatlead from the main trolley line into the sidepassages or headings.

The object of my invention is to provide a section switch of theabove-indicated character that shall be simple and inexpensive use inmines and in other trolley systems where it may be necessary to cut asection of the line out of circuit, are usually made up of a largenumber of parts. They are therefore relatively expensive, especially inview of the fact that switches of this type are seldom operated, beingonly required for emergency use, as when a mine trolley becomes groundedby a fall of rockor the like. A further disadvantage of the existingforms of section switches is that the sectionalizing is usuallyaccomplished by in serting a block of insulating material between theconducting end pieces or runners, and this insulation must generally beseveral inches in length, in order to provide sufficient creepagedistance between the separated ends of the conductors. When such adevice is in service, and the switch is closed, every motor that passesmust lose its current for an appreciable interval, and

the sudden rush of current that follows when the insulating break ispassed 1s a severe strain upon the motor. Furthermore, it sometimeshappens that a heavily loaded car will stop with the trolley wheelresting against the insulating spacing block, and considerableinconvenience and loss of time are caused in again starting the car.

According to my present invention, I avoid all of the foregoingdisadvantages, and, in addition, produce a device of extreme simplicity,in which two end pieces or runners are supported upon an insulatingblock and separated by a relatively short air gap, both sides of whichare engaged by a trolley wheel passing the switch. The adjacent ends ofthe runners are preferably so modified as to provide a long creepagedistance between the runners, which are electrically connected by meansof a simple form of switch.

For a better understanding of my invention, reference may now be had tothe accompanying drawing, which illustrates the preferred form of myinvention. Two metallic end pieces or runners 1 and 2 are secured to thelower edge of a block 3, of wood or other suitable insulating material,by means of two short tap bolts 4 and 5 and two longer tap bolts 6 and7. The bolts 4: and 5 are countersunk in the top of the block 3, insuitable holes which are fitted with plugs 8. The bolts 6 and 7 extendabove the block 3 and are provided with fiat heads 9 and 10 that areperforated to receive a sliding switch rod 11 to which is attached ahandle 12. The hole in the head 9 is slightly tapered in order that therod 11 may be firmly seated in its contact-making position.

The outer ends of the runners 1 and 2 are provided with the usualopenings 13, for receiving line wires 14: and 15, and set screws 16 aredisposed in threaded holes transverse to the openings 13 for fasteningthe line conductors in place. It is to be noted that the trolleyconnections just described are formed integral with the runners, whichis a feature of simplicity and compactness.

The inner ends of the runners 1 and 2 are separated by an air gap 17which I prefer to make about 5; of an inch. wide, but which may be wideror narrower, if desired, without impairing the utility of the device. Inorder to increase the creepage distance between the runners, I cut away"the metal from the upper sides of the adjacent runner ends, as shown at18. This arrangement does not seriously affect the rigidity of the .1and 2 as much as possible, I prefer to cut away iportionsfrom theirupper edges, as

:shown at 19, leaving the full thicknessat itlle 'pointswherethefastening bolts 4:, 5, 6 :and 7 are'tapped in. By this means, I make*u-seof a minimum amount of metal, which 31S usually expensive brass,wlthout sacrifice --1ng rigidity or strength.

In order to reinforce the wooden block, transverse bolts and 21 may bepassed through suitable openings near the endsof the block, and fastenedin place by means of suitable washers and nuts. A hanger 22 -may 'bescrewed to the top of the block 3,

and wires may be passed through holes in this hanger for the purpose ofsuspending the switch its operative position.

- The location of the sliding switch, on top of the insulating block 3,is a decided advantage,-since the switch rod and handle are protectedfrom damage which may be caused by atrolley pole ifthe trolleywheelshould jump from the wire in the vicinity of the switch. Ifdesired,however, the switeh'may be placed upon :the side of the block, and

any other suitable switch may be substituted for the specific form whichI have shown and described. I prefer theslidingitypeof switch for useinmines, becausethe trolley conductors are usually located so near theroof of the mine that little space is le'ft for j operating pivotedknife switches and the :like.

Inthenormal operation of the trolleyline in which my improved device isinsertedythe ;sl1d1ng switch is closed, the rod llbeing in dthe posltlonshown. The bolts 6 and 7 ,to-

:gether with the switch rod '11 then form'a V shuntior jumper-connectionaroundthe air gap 17, and trolley wheels, when they pass across theswitch, will engage therunner on the farther side of the air gap beforeleav- 'ing' the other runner.

The current thereforepasses contlnuouslyto the motor, withoutthe'interruptions and-consequent strains upon the moto'r which I havementioned vabove. When it is necessary to cut out-of lci-rcuit thesection of the line onthe-side of This construction I such :as areindica -cla1ms.

the switch away from the generator, the switch rod 11 is removedby meansof the handle 12. The device then serves as an effective break in 'theconductor, since the long creepage distance described above preventscurrent from leaking from one line conductor to the other, and since theair .gap 17 prevents direct passage of current. No ipermanentrarccan bemaintained across the air gap, even if a car should, cross it, for theouter endof theicut out sectio11+is generally :dead-ended, and itiisJon'ly inecessary to throw off the controller .of tlIBlCZLI' .in:orderto permanently extinguish anyaarc ithat unight :be struck across thegap.

:It is obvious that :the details 10f the struce ture which .1 have;shown and described may be variously modified by persons skilled in theE art without departing from :thespirit --and scope of my tinventiomandiit is therevsforesto beaunderstoodithatwno linntationsare to :beimposed 1113011 my invention :excep't ted .in the appended :I claimzasmy inventionrl 3 i l '1. A section switch; 'for :trolley systemscomprising a supporting .;block of insulataingamaterial,two'longitudinally a'linedesolid. -end pieces of conducting unateria'lattached :to the lower edge of the said block: and'hav- -ing. their :adjace'nt: opposed. ends separated only by an .air gapsuiiicientlynarrowto permita trolley \wheel to engage 'both of the said end piecesatonee and wide 1 enough :to

prevent arcing across the air gap'kunder -op- -v crating conditions, thesaid adjacent endsof the end pieces being cut away to a substantialextent :to provide an increased creepage path around =thesa1d a r gap,means for; attaching trolley conductorsfltoithej said end .;pieces, aplurality of {fasteners extending throughthesaid block and-serving toattach the said end pieces thereto, and a switch member adaptedtoelectrically connect and disconnectthe said endpieces.

2. A section switch for trolleysystems comprising a block. of insulatingmaterial, two longitudinally alined end pieces wattached to one edge ofthesaid-block and "having their adjacent opposed endswseparated by anairgap, sufficiently irestricted to' permit a trolleywheeltokengagebothofcthe saidend pieces at onceandisufiiciently wide to prevent arcingacross-thegap under operating conditions, the outer ends of the" saidend pieces being provided with means for .securing trolley conductors:thereto, -:means comprising fasteners extending through the said blockand into the said end pieces, for

attaching the said end piecesrto :thesaid block, the said attachingzmeansvser vijng :also

as stationary switch contact -members,;and

a movable contact member adapted {to connect and LllSCOIlIlGGtillG.saidlstatiouargy .con-

. tact members. a I

3. A section switch for trolley systems comprising a supporting block ofinsulating material having downwardly converging sides, twolongitudinally alined solid end pieces of conducting material attachedto the narrowed lower edge of the said block and having their adjacentopposed ends separated by an air gap sufficiently narrow to permit atrolley wheel to engage both of the said end pieces at once and withoutshock, but wide enough to prevent arcing across the air gap underoperating conditions, the said adjacent ends of the end pieces being cutaway substantially parallel to their trolley-engaging surfaces to asubstantial extent to provide an increased creepage path around the saidair gap, a plurality of attaching screws extending through the saidblock and received in screw-threaded openings in the said end pieces,and a switch member adapted to electrically connect and disconnectcertain of the said screws.

In testimony whereof I have hereunto subscribed my name this 26th day ofApril 1915.

HARRY W. DAVIS.

Witnesses:

B. B. HINES, R. D. BROWN.

Gopies of this patent may be obtained for five cents each, by addressingthe Commissioner of Eatents, Washington, D. G.

